Fluorosilicone rubber (FMVQ) is a linear polymer with silico-oxygen bond as the main chain structure and fluoroalkyl or fluoroaryl groups introduced into the side chain, so it is also called oil-resistant silicone rubber. There are many varieties of fluorosilicone rubber, of which the mass production and widely used is poly (3,3, 3-trifluoropropyl methyl) silicone rubber, whose vinyl content is usually less than 0.5%.
Abnormal production of fluorine silicone rubber and its solution
Mixed fluorine glue appears dead material
The reason is that the ingredients are exposed to sulfur or sulfur-containing products, many companies do not have a special fluorine rubber machine, often after refining other sulfur-containing rubber, cleaning is not in place, or the ingredients are accidentally stained with sulfur or water, which can be combined with the accelerator in fluorine rubber cause scorch, or because of the action of water to activate the fluorine rubber surface decomposition. Solution, the best special machine, if it can not be done, should also be in the conversion of fluorine rubber, be sure to completely clean the baffle and tray, to avoid contact with water and sulfur, ingredients applied special tools, one scoop, to prevent cross-contamination. Calcium hydroxide and magnesium oxide remain sealed and ready to use.
Sticking roll phenomenon
Mainly in the mixing process of the open mixer, the rubber material is tightly packed in the back roller, or the two rollers are packed at the same time, resulting in the former rubber material can not be turned, and the latter has the added compounding agent is easy to press into a sheet and fall, resulting in uneven dispersion. The main cause of fluorine adhesive roller is low Mooney or low molecular content of fluorine adhesive. The solution to this problem is to choose raw glue with Mooney viscosity of about 70 when selecting glue, and choose raw glue with narrow molecular weight distribution, and then add a small amount of Brazilian wax or fluorine wax, or low molecular weight polyethylene in the formula, which can also solve the sticky roll phenomenon.
Small white spots appear in the compound
This is due to the uneven dispersion of some powder of the fluorine adhesive compound, or because the powder is wet and granulate, such as acid absorption agent calcium hydroxide, magnesium oxide and diatomaceous earth, barium sulfate, etc., the solution is to prevent the moisture of the compound and strengthen the thin pass process.
Product tear easily
The cause may be that the raw edge is too thick, tearing when trimming the edge, or the mold is too tight, the raw edge part is stuck by the mold when the mold is out, and it is easy to tear from the product and the raw edge before the force is uneven when the mold is drawn, and it is easy to tear the product. Sometimes the mold cavity processing is rough, or the glue sticks to the mold, and when the vulcanization is finished, the mold is difficult to release and easy to tear the product. In addition, the vulcanization temperature is too high, will also make the product brittle, easy to tear. In view of the above anomalies, it can be solved from the following aspects: the mold processing accuracy should be well mastered cavity roughness Ra is less than 0.8, the matching gap should not be too large, the vulcanization temperature is controlled between 170 degrees, and the rubber material weighing should be accurate.
Shrinkage crack problem
Because the pressure is removed when the mold is opened, the fluorine rubber shrinks, and the raw edge part is stuck between the mold mating surface, so a tensile force is generated between the product part and the raw edge, so that the product and the raw edge are split, and when the crack expands to the product part, it causes the shrinkage cracking phenomenon. The solution is to appropriately reduce the vulcanization temperature, choose the Mooney viscosity to be appropriate, and the mold fit should be appropriate, not too loose and too tight.
Edge burning
It is caused by too high vulcanization temperature, especially for thick products, and can be overcome by appropriately reducing the vulcanization temperature.
There's a mark on the joint
It is because the adhesive material in the lap part is not fully integrated together, or because the rubber strip has impurities or oil, the solution is to keep the preformed rubber strip clean during storage, transportation and gluing to prevent pollution.
Short stock
This is related to the mold structure and the fluidity of the compound. The closed mold is more likely to lack glue than the open mold. The solution is to properly adjust the fluidity of the rubber material and open the vent hole on the mold cavity.
Product distortion
This is due to the fluorine rubber shrinkage rate is large, the product shrinkage anisotropy is large after molding, the thermal expansion coefficient of the rubber in different directions is different, the second stage of vulcanization process will form a number of diplomatic links, especially a stage of sulfur, the second stage of vulcanization after the product, more obvious deformation, so it is necessary to give full crosslinking in a period of vulcanization time to avoid product deformation after the second stage of vulcanization.
Serious mold pollution phenomenon
In the vulcanization process there will be HF generation, it is a very acidic substance, has a great corrosion effect on the mold, the formulation is to add acid absorption agent is to absorb the generated HF, to prevent mold pollution. The solution is to migrate to the rubber surface during vulcanization to form a film to prevent the mold from being polluted. In addition to the mold to be electroplated, fluorine release agent can also be used to protect the mold from pollution.